You can't see the pictures now, because they are "awaiting approval".
You need to clean the cooler fins from the inside. My pictures will show you where most of the dust sticks. Then you will see what i mean.
Have a second look to the ebay picture of your cooler/fan combination. There are four black screws holding the metallic cover of the fan. Have you removed that cover to get to this inside position?
If you clean with a vacuum cleaner, i recommend to lock the fan in any case. It may take damage, if it is rotated by an external force like a vacuum cleaner.